1. Field of the Invention
This invention relates to electrostatic copier devices and more particularly to a fuser oil application mechanism for fixing stations of such devices.
2. Prior Art
Machines which work on electrostatic principles such as electrostatic copiers or printers are generally well known to the art. See for example U.S. Pat. No. 3,515,855. Such copiers or printers, can operate either by electrographic or electrophotographic principles. In electrophotographically operating devices a latent image charge pattern of the symbol or image to be reproduced or printed is generated on an intermediate carrier. The intermediate carrier may be a photoelectrically coated drum. Thereafter portions of the charge surface of the intermediate carrier are partially or totally discharged by exposure to produce the latent image. The latent image is then developed at a developing station in which the discharged zones of the intermediate carrier surface are coated with toner to produce a toner image. The toner image is then transferred from the intermediate carrier to a recording carrier at a transfer station. The recording carrier may be a sheet of paper or a paper web.
The toner images must thereafter be fused to the recording carrier at a fixing station.
Charge patterns can also be produced by the electrographic principle such as with the aid of electrode combs. Further it is known to generate the charge pattern directly on the recording carrier thereby eliminating the intermediate carrier. Finally it is also possible to produce toner images directly on the recording carrier. In all of these methods, it is necessary, or desirable, to fix the toner image on the recording carrier so as to make the image unblurable.
Designs for such fixing stations are known such as, for example that shown in U.S. Pat. No. 3,324,791. In that construction the fixing station consists of two fixing rollers between which the recording carrier carrying the toner image is passed. One of the rollers is heated. The heated roller generally contacts the side of the recording carrier containing the toner image. That heated roller is herein called the fixing roller. The other roller presses the recording carrier against the fixing roller. The toner image is fused onto the recording carrier by the application of heat and pressure from the rollers or cylinders.
One disadvantage with fixing devices of this type is that some toner and/or other debris may adhere to and remain on the surface of the fixing roller. In order to prevent depositation of toner particles on the fixing roller a fuser oil, generally a silicon oil, is applied to the fixing roller surface. Application of the fuser oil can be by means of a wick arrangement. A design for such a wick arrangement is shown in U.S. Pat. No. 3,324,791. In that construction a fuser oil roller dips into a container of fuser oil. The roller transfers fuser oil from the container to a wick which has a portion thereof contacting the surface of the fuser oil roller and another portion riding on the surface of the fixing roller. The fuser oil is thus transferred from the surface of the fuser oil roller to the surface of the fixing roller by the wick.
A disadvantage of this type of arrangement arises from the fact that dispite the application of the fuser oil to the fixing roller surface, it is impossible to totally eliminate deposit of paper dust or toner particles on that surface. With prolonged use of the fixing station, those deposits will be, at least in part, transferred to the wick thereby making the wick dirty. As a result the wick must be changed. It can become necessary to change the wick relatively frequently particularly when high fixing speeds are utilized.
Another disadvantage of the prior art wick arrangements is the fact that the wick extends over the entire axial extent of the fixing roller and it is not possible to coat isolated axial areas or zones of the fixing roller surface. However, since the fixing roller may have a maximum recording carrier contact length which is determined by the maximum width of the recording carrier being used in the device, when narrower recording carriers are used, this results in a waste of fuser oil to coat portions of the fixing roller which will not be in contact with the narrower data carrier.
It would therefore be an advance in the art to provide a construction which substantially reduces the necessity of changing the wick to replace a dirty wick and which further allows the fixing surface to be coated with fuser oil only in those areas which are subject to contact with the particular width of data carrier then being used in the machine.